Downloading pornography using a BitTorrent file-sharing program may lead to treacherous legal territory. South Florida residents increasingly are the targets of controversial copyright suits filed by adult-film producers.

Since January 2011, those producers — many based in California and other parts of the country — have filed 40 lawsuits in federal court in Broward, Palm Beach and Miami-Dade counties seeking the identities of more than 1,000 people accused of illegally downloading copyrighted adult films.

Critics of the porn producers' legal tactics, including a few federal judges, say the suits are designed to extract thousands of dollars from individuals without having to prove their cases in court. They also say the producers likely have collected millions of dollars in settlements from people who don't want to be publicly linked to pornography, or don't have the means to defend themselves.

"It is terrifying to get one of these letters and not be pressured into settling," said Rebecca Jeschke, a spokeswoman for the Electronic Frontier Foundation in San Francisco, which has filed court briefs on behalf of defendants named in the copyright suits.

"The real issue here is the minute someone's name is released to these 'copyright trolls,' it's game over. The settlements are often less than the cost of defending yourself," she said.

The adult-film produceers are following a once-successful legal strategy developed a decade ago by the music industry, which sued tens of thousands of individuals for illegally downloading music, a practice the industry ended several years ago.

The three latest South Florida lawsuits were filed May 11 in federal court in West Palm Beach. Two California pornography producers allege 28 "John Does," whose Internet addresses are listed as originating from Palm Beach Gardens to Boca Raton, violated their copyrights.

Miami attorney M. Keith Lipscomb, who represents the two producers, said in an email statement the newest suits target "the worst-of-the-worst habitual infringers" who have illegally downloaded scores of films from his clients and others.

He said his clients have no choice but to sue to prevent further harm to their businesses, which have been hurt by the spread of file sharing on the Internet. "It is not a victimless crime. It is theft, and it costs jobs," he said, adding he will seek "substantial" damages from copyright violators.

The adult-film producers don't know the identities of the people who used BitTorrent clients to share their films, so they name "John Does" and then try to win court approval to force Internet providers to identify them. Once the producers have that information, defendants receive letters or phone calls demanding a settlement.

"All these people get this letter. What the plaintiff is saying is we are going to sue you for copyright infringement and make it look like you are downloading adult films," said Miami attorney Kubs Lalchandani, who has successfully defended the copyright cases.

"It's like a bad-debt collector when they call. I have had people tell me they were told they could go to jail for this, which is false. You can imagine the stress associated with this," he said.

There are pitfalls for the plaintiffs in mass-defendant suits, which may not target the correct individuals, Lalchandani said, especially if the individuals did not have a secure home WiFi network, leaving it open to anyone.

"You are making yourself very vulnerable to these kinds of cases," he said.

Since BitTorrent users share small pieces of files containing music, movies or software until a complete file is assembled, the adult-film producers sue dozens or even hundreds of defendants at a time — alleging they were working in concert to violate copyright law.

Some federal judges have begun frowning on multiple-defendant suits, calling them an "abusive litigation tactic." A federal judge in New York wrote that the cases before him were part of "a nationwide blizzard" of such suits, in a May 1 ruling limiting the producers to only one defendant per case.

In South Florida, U.S. District Judge M. Kenneth Moore in Miami has dismissed several suits as abusive litigation.

When Moore dismissed one case in December, he wrote it "appears plaintiff is pursuing a litigation strategy whereby plaintiff joins a number of unknown defendants in a single suit, obtains identifying information through discovery and is then content to extract settlements from the defendants without any intent to litigate the matter further."

Lipscomb pointed out that other judges in Florida have found it is proper to name multiple defendants in the suits.

Jeschke said the Electronic Frontier Foundation does not support copyright violators, but it opposes the "business model" the adult-film producers are pursuing.

"The legal system is not supposed to be used this way, as a scheme to get defendants to settle without ever properly filing a lawsuit," she said.

Lalchandani agreed the suits are a means for the pornographers to make more money, in a commodity industry that has been undercut by a proliferation of small production companies and even amateurs on the Internet.

"Porn is so cheap, and so easy to get, they can't make money at it," he said. "They look for new revenue. This is how they get it."